The present invention relates to patient supports, more particularly to a reclining, chair-type patient support that automatically moves away from a wall as the backrest reclines. Specifically, the invention relates to a transverse motion linkage for a dental patient chair.
Patient supports of the type contemplated by this invention have a seat member with a backrest attached at one end and a legrest attached at the other end. The entire patient support can be raised and lowered, for allowing the patient to enter and exit, and for positioning the patient in order to be worked on.
Efficient use of office space is always an important consideration when planning the layout of a doctor's office, such as a dental operatory. One of the most space consumming pieces of equipment in the office is the patient support. Space must be allowed for the fully extended dimensions of the patient support, as well as for work space surrounding it.
A problem with reclining-back patient supports prior to the present invention was that additional room had to be left behind them, in order to accommodate for arcuate movement of the upper end of the backrest as it swings down toward a horizontal position. Furthermore, that swinging movement gave patients an unpleasant sensation of falling as the backrest dropped toward the floor.
Another problem that has remained unsolved until the present invention was that complex mechanisms were required for coordinating the lifting of a legrest with the reclining of a backrest, especially when providing for "close to the wall" positioning. A parallel bar linkage system has been used for imparting transverse, away-from-the-wall movement to a reclining chair. Reclining the backrest and simultaneously lifting the legrest was accomplished by manually pushing against stationary armrests from a seated position. The linkage systems used for this have been quite complicated, and would not be usefull for a patient support because they were designed to operate by manual movement rather than by motorized movement, and usually provided only two, pre-set positions. The full range of adjustability required for a patient support was not attainable.